The invention relates to biodegradable compositions for sustained-release drug delivery and methods for administering a biologically active substance via these compositions.
Rapid advances in the fields of genetic engineering and biotechnology have led to the development of an increasing number of proteins and polypeptides that are useful as pharmaceutical agents. The development of methods for administering these new pharmaceutical agents is thus becoming increasingly important.
Most proteins have relatively short half-lives, requiring frequent administration to achieve efficacious blood levels. To increase patient convenience and to improve efficacy and safety by keeping blood levels within the therapeutic range, smoothly releasing injectable depot formulations of protein drugs are highly desirable.
Recent polymer developments have improved the ability to deliver proteins and peptides by allowing for slower and steadier release of the molecule in the patient""s system. However, in many cases, the active form of the protein is difficult to formulate in biodegradable polymers. Synthetic materials, such as biodegradable hydrogels, have also been developed for use in delivering proteins. Despite the advances provided by the available polymers and hydrogels, the delivery of protein to the systemic and local circulation is still relatively rapid, in some cases too rapid to allow this route of administration to be used.
The present invention features articles for delivery of a biologically active substance (hereafter xe2x80x9cBASxe2x80x9d), and methods for making such articles. The articles of the invention improve the bioavailability of the BAS by formulating the BAS in an insoluble form. The invention also features methods of treating an animal using the articles for delivery of a BAS.
Accordingly, in a first aspect the invention features a biocompatible therapeutic article for delivery of a BAS, comprising a macromer, a molecule or mixture of molecules which preferentially excludes proteins, and the BAS, wherein the BAS is in an insoluble format upon completion of the formulation of the article comprising the macromer, molecule, or mixture of molecules which preferentially excludes proteins, and BAS.
In a preferred embodiment of the first aspect of the invention, the biocompatible therapeutic article has at least one of the following properties: the BAS is less than 15% aggregated; the article contains at least 10% macromer and at least 5% BAS, as measured by dry weight; the time at which 5% of the releasable BAS is released from the article is greater than {fraction (1/16)} of t50; or the t50 is greater than or equal to ⅝ of t80. More preferably the biocompatible therapeutic article has at least two of the above properties. Most preferably, the biocompatible therapeutic article has all of the above properties.
In another embodiment of the first aspect of the invention, the molecule which preferentially excludes proteins is a macromer, poly(ethylene glycol), hyaluronic acid, or poly(vinylpyrrolidone). In yet another embodiment, the macromer is a hydrogel. In still another embodiment, the solubility of a protein in the article comprising the macromer, molecule that preferentially excludes proteins, and BAS is less than 5-10 mg/ml, and more preferably is less than 1 mg/ml.
In another embodiment of the first aspect of the invention, the mixture of molecules comprises a positively charged ion-carrying reagent, for example, triethanolamine or Tris, when the pH is such that the protein is negatively charged. In still another embodiment, the mixture of molecules comprises a negatively charged ion-carrying reagent, such as sodium dodecyl sulfate, when the pH is such that the protein is positively charged. In yet another embodiment, the mixture of molecules comprises a surfactant, for example, Tween 20, Tween 80, or poloxamer F68. In a second aspect, the invention features a method for making a therapeutic article for delivery of a BAS, involving (a) combining the BAS with a molecule or mixture of molecules which preferentially excludes proteins; (b) combining the mixture formed in step (a) with a macromer, wherein the BAS is in an insoluble form and remains insoluble upon combining with the molecule or mixture of molecules which preferentially excludes proteins and the macromer; (c) forming a mixture of the combination formed in step (b); and (d) polymerizing the mixture to form an article.
In one embodiment of the second aspect of the invention, steps (a) and (b) are combined into a single combination step.
In a preferred embodiment of the second aspect of the invention, the biocompatible therapeutic article has at least one of the following properties: the BAS is less than 15% aggregated; the article contains at least 10% macromer and at least 5% BAS, as measured by dry weight; the time at which 5% of the releasable BAS is released from the article is greater than {fraction (1/16)} of t50; or the t50 is greater than or equal to ⅝ of t80. More preferably the biocompatible therapeutic article has at least two of the above properties. Most preferably, the biocompatible therapeutic article has all of the above properties.
In another embodiment of the second aspect of the invention, the molecule which preferentially excludes proteins is a macromer, poly(ethylene glycol), hyaluronic acid, or poly(vinylpyrrolidone). In yet another embodiment, the macromer is a hydrogel. In yet another embodiment, the macromer is a hydrogel. In still another embodiment, the solubility of a protein in the article comprising the macromer, molecule that preferentially excludes proteins, and BAS is less than 5-10 mg/ml, and more preferably is less than 1 mg/ml.
In another embodiment of the second aspect of the invention, the mixture of molecules comprises a positively charged ion-carrying reagent, for example, triethanolamine, when the pH is such that the protein is negatively charged. In still another embodiment, the mixture of molecules comprises a negatively charged ion-carrying reagent, such as sodium dodecyl sulfate, when the pH is such that the protein is positively charged. In yet another embodiment, the mixture comprises a surfactant, for example, Tween 20, Tween 80, or poloxamer F68.
In a third aspect the invention features a method of treating an animal, involving administering the biocompatible therapeutic article of the first aspect of the invention to a mammal. Preferably the mammal is a rodent, and most preferably the mammal is a human.
In yet other preferred embodiments, the articles are administered to the lung of the mammal, or are administered intravenously, subcutaneously, intramuscularly, orally, or nasally.
In a preferred embodiment of any of the above aspects of the invention, the macromer comprises: (a) a region forming a central core; (b) at least two degradable regions attached to the core; and (c) at least two polymerizable end groups, where the polymerizable end groups are attached to the degradable regions. In preferred embodiments, the region forming a central core is a water soluble region. The water soluble region may be poly(ethylene glycol), poly(ethylene oxide), poly(vinyl alcohol), poly(vinylpyrrolidone), poly(ethyloxazoline), poly(ethylene oxide)-co-poly(propylene oxide) block copolymers, polysaccharides, carbohydrates, proteins, and combinations thereof. The degradable region is selected from the group consisting of poly(xcex1-hydroxy acids), poly(lactones), poly(amino acids), poly(anhydrides), poly(orthoesters), poly(orthocarbonates), and poly(phosphoesters). Preferably, the poly(xcex1-hydroxy acid) is poly(glycolic acid), poly(DL-lactic acid), or poly(L-lactic acid), and the poly(lactone) is poly(xcex5-caprolactone), poly(xcex4-valerolactone), or poly(xcex3-butyrolactone). In another preferred embodiment, the degradable region comprises poly(caprolactone). In yet another embodiment, the polymerizable end groups contain a carbonxe2x80x94carbon double bond capable of polymerizing the macromer.
In other embodiments of the above aspects of the invention, the macromer includes: (a) a water soluble region comprising a three-armed poly(ethylene glycol) with a molecular weight of 3,000 to 6,000 daltons; (b) lactate groups attached to the region in (a); and (c) acrylate groups capping the region in (b). The macromer may alternatively include: (a) a water soluble region comprising poly(ethylene glycol) with a molecular weight of either 2,000 or 3,400 daltons; (b) lactate groups on either side of the region in (a); and (c) acrylate groups capping either side of the region in (b). In another alternative, the macromer may include (a) a water soluble region comprising poly(ethylene glycol) with a molecular weight of 3,400 daltons; (b) caprolactone groups on either side of region in (a); and (c) acrylate groups capping either side of the region in (b).
In still other embodiments of any of the above aspects of the invention, the article includes at least 5%, more preferably 10%, and most preferably 20-30% active substance by dry weight. In still another embodiment, the article is biodegradable.
In a more preferred embodiment of any of the above aspects of the invention, the macromer includes a water soluble region consisting of a three-armed PEG with a molecular weight of 4,200 to 5,400 daltons; lactate groups one end of each arm of the PEG; and acrylate groups capping the lactate groups.
In another more preferred embodiment of the above aspects of the invention, the macromer is made of a triad ABA block copolymer of acrylate-poly(lactic acid)-PEG-acrylate-poly(lactic acid)-acrylate. The PEG has a MW of 3,400 daltons; the poly(lactic acids) on both sides had an average of about five lactate units per side; and the macromer is therefore referred to herein as xe2x80x9c3.4kL5.xe2x80x9d In another more preferred embodiment, a lower molecular weight PEG, such as MW 2,000 daltons PEG is used in place of the MW 3,400 PEG, and the resulting macromer is abbreviated as xe2x80x9c2kL5.xe2x80x9d
In yet another more preferred embodiment of the above aspects of then invention, the macromer is an acrylate-PCL-PEG-PCL-acrylate macromer. The PEG has a MW of 3,400 daltons and has polycaprolactone on both sides, with an average of about 6 caproyl units per side. This macromer is referred to herein as xe2x80x9c3.4kC6.xe2x80x9d
In other preferred embodiments, the BAS is a protein or peptide. More preferably the protein is chosen from a group consisting of hormones, antibodies, differentiation factors, angiogenic factors, enzymes, cytokines, chemokines, interferons, colony-stimulating factors, and growth factors. Most preferably, the protein is a hormone, such as human growth hormone, or a peptide, such as LHRH.
In still other embodiments of the second and third aspects of the invention, the therapeutic articles release at least 80% of the BAS at a time 1xc2xc times greater than t50. At least 80% of the therapeutic articles may have a particle size of less than about 80 microns. The water soluble region may consist essentially of PEG having a molecular weight of about 500 to 20,000 daltons, and more preferably, between 1,000 and 10,000 daltons. The degradable region may comprise a blend of at least two different polymers. In addition, the macromer may be non-degradable.
In still other embodiments of the second and third aspects of the invention, the therapeutic article is capable of releasing the BAS for at for a period of time at least 2 times greater than t50. The article is also capable of delivering a therapeutic dose of the BAS for at for a period of time at least 1xc2xc times greater than t50.
By xe2x80x9cmacromerxe2x80x9d is meant a polymer with three components: (1) a biocompatible, water soluble region; (2) a biodegradable/hydrolyzable region, and (3) at least two polymerizable regions.
By xe2x80x9cbiologically active substancexe2x80x9d or xe2x80x9cBASxe2x80x9d is meant a compound, be it naturally-occurring or artificially-derived, that is incorporated into an article and which may be released and delivered to a site. Biologically active substances may include, for example, peptides, polypeptide, proteins, synthetic organic molecules, naturally occurring organic molecules, nucleic acid molecules, and components thereof.
By xe2x80x9ca molecule or mixture of molecules that preferentially excludes proteinsxe2x80x9d is meant a molecule or mixture of molecules, be it naturally-occurring or artificially-derived, that, when added to a solution, confers a lower level of solubility of the protein or polypeptide in said solution. Preferably, protein solubility will be decreased 50-fold; more preferably, 100-fold and most preferably about 200-fold. Preferably the solubility of a protein in a solution that includes said molecule or mixture of molecules that preferentially excludes proteins is less than 5-10 mg/ml, and more preferably is less than 1 mg/ml.
By xe2x80x9csubstantially pure polypeptidexe2x80x9d or xe2x80x9cproteinxe2x80x9d is meant a polypeptide or protein that has been separated from the components that naturally accompany it. The terms polypeptide and protein may be used interchangeably. Typically, the polypeptide is substantially pure when it is at least 60%, by weight, free from the proteins and naturally-occurring organic molecules with which it is naturally associated. A substantially pure polypeptide may be obtained, for example, by extraction from a natural source (e.g., a cell expressing the desired polypeptide), by expression of a recombinant nucleic acid encoding a desired polypeptide, or by chemically synthesizing the polypeptide. Purity can be assayed by any appropriate method, e.g., by column chromatography, polyacrylamide gel electrophoresis, agarose gel electrophoresis, optical density, or HPLC analysis.
A protein is substantially free of naturally associated components when it is separated from those contaminants which accompany it in its natural state. Thus, a protein which is chemically synthesized or produced in a cellular system different from the cell from which it naturally originates will be substantially free from its naturally associated components. Accordingly, substantially pure polypeptides include those derived from eukaryotic organisms but synthesized in E. coli or other prokaryotes.
By xe2x80x9cpurified nucleic acidxe2x80x9d is meant a nucleic acid that is free of the genes which, in the naturally-occurring genome of the organism from which the nucleic acid of the invention is derived, flank the gene. The term therefore includes, for example, a recombinant DNA which is incorporated into a vector; into an autonomously replicating plasmid or virus; or into the genomic DNA of a prokaryote or eukaryote; or which exists as a separate molecule (e.g., a cDNA or a genomic or cDNA fragment produced by PCR or restriction endonuclease digestion) independent of other sequences. It also includes recombinant DNA which is part of a hybrid gene encoding additional polypeptide sequence.
By xe2x80x9cbiocompatiblexe2x80x9d is meant that any compound or substance which is administered to a subject, cell, or tissue is used to treat, replace, or augment a function of the subject, cell or tissue, and is not harmful to said function.
By xe2x80x9cinsolublexe2x80x9d is meant that the solubility of a compound is less than 1 g/100 ml in a solution. The solution may be an aqueous solution, an organic solvent, such as dimethylsulfoxide, or a mixture of aqueous and organic solvents. As used herein, a BAS is in an insoluble format upon completion of the formulation for a therapeutic article for delivery of the BAS. The BAS remains in an insoluble format upon delivery of the therapeutic article to a patient, and is then slowly released at a controlled rate for localized or systemic delivery to the patient.
As used herein, by xe2x80x9caggregatedxe2x80x9d is meant that a BAS is releasable as individual molecules. The percent of a BAS in an article which is aggregated can be determined, for example, by SEC-HPLC.
By xe2x80x9ctherapeutic dose,xe2x80x9d when referring to a BAS, is meant a plasma level between the minimum effective level and the toxic level.
By a xe2x80x9cmixturexe2x80x9d is meant a composition in which all of the compounds contained in the composition are evenly distributed.
As used herein, by xe2x80x9cpore sizexe2x80x9d is meant the dimensions of a space in the intact polymer through which a macromer, component of a macromer, or a BAS potentially can pass. Pore sizes which are utilized as part of the invention are those smaller than the BAS as it is present in the particular embodiment (e.g., a protein molecule, or aggregate thereof).
As used herein, by xe2x80x9cperiod of releasexe2x80x9d is meant the length of time it takes for a specified percent of the BAS to be released from an article. The period of release may be assessed, for example, by measuring the time it takes for 50% or 80% of the BAS to be released from the article.
By xe2x80x9clow burst effectxe2x80x9d is meant that the amount of BAS released from an article is released relatively steadily over time, rather than at an initial fast rate, followed by a slower rate. For example, a BAS has a low burst effect (e.g., less than or equal to 20% burst) upon release from an article when the period of release for 5% of the releasable BAS is greater than {fraction (1/16)} of t50, or when the t50 is greater than or equal to ⅝ of t80. In contrast to a low burst article, a high burst article (e.g., one which rapidly releases 30% of the BAS) might release 5% of its releasable BAS in less than {fraction (1/18)} of t50 and have a t50 equal to xc2xd of t80.
A specific example of a low burst product of the present invention is one in which less than 20% of the BAS comes out in the first day for a product designed to release a BAS for 10 days.
By xe2x80x9ct50xe2x80x9d is meant the time at which 50% of the original load of BAS has been released. As used herein, preferably 5% of the releasable BAS is released at a time which is greater than {fraction (1/16)} of t50, or the t50 is greater than or equal to ⅝ of the t80.
By xe2x80x9ct80xe2x80x9d is meant the time at which 80% of the original load of BAS has been released. As used herein, preferably 5% of the releasable BAS is released at a time which is greater than {fraction (1/16)} of t50, or the t50 is greater than or equal to ⅝ of the t80.